Fossils discovered at a secret location in Australia's 'dead heart' are extremely rare and delicate

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Thousands of preserved plants, spiders, and insects from the Miocene Epoch were discovered by scientists.

An extraordinary collection of fossils from Australia's so-called dead heart has been unearthed for the first time. These include fossils of trapdoor spiders, huge cicadas, little fish, and an old bird's feather.

More than a century ago, a team of palaeontologists led by British geologist John Walter Gregory found the fossil treasure trove known as a Lagerstätte ("storage site") in New South Wales. For the safety of the scientists excavating the remains of plants and animals that lived there between 16 million and 11 million years ago, the Lagerstätte's location on private land was kept hidden.

For the first time, fossils from the Miocene Epoch (23 million to 5.3 million years ago) have been uncovered in Australia, according to new research. Bones and teeth from larger creatures, which are well-preserved in Australia's dry terrain, accounted for the majority of previous Miocene discoveries there. The new cache contained a variety of Miocene rainforest plant fossils, including spiders and insects.

Using scanning electron microscopes (SEMs), the researchers could get down to the level of individual cells and subcellular components in the well-preserved fossils. Fish, larvae, and a dragonfly wing that had been partially digested inside a fish's stomach were all visible in the photographs. A mussel adhered to a fish's fin, and pollen grains were found on insects' bodies in other fossilised pictures.

Australian Museum palaeontologist Matthew McCurry tells Live Science that this find provides "unique insight into what these ecosystems were like." Our knowledge of the ecosystems' diversity, species' presence, and interactions amongst them have increased dramatically.

Before that year, a farmer reported finding petrified leaves on the location, now known as McGraths Flat, by palaeontologists. According to McCurry, when the scientists studied the site, "we were happy to discover that the location offers a far wider range of fossils," including insect, spider, and fish remnants.

By McCurry's estimation, palaeontologists have only unearthed slightly more than half of the estimated 11,000 to 22,000 square feet of fossil-bearing rock. Above the sandstone, an iron-rich rock matrix known as goethite encased the fossils. After runoff from neighbouring basalt cliffs poured into the pool, known as a billabong in Australia, plants and animal bones in a stagnant pool were likely covered in iron and other minerals, which preserved them in exquisite detail.

Researchers are now beginning to piece together the fossils to create a picture of a vanished Australian rainforest that existed millions of years ago. According to the study, the authors found leaves from flowering plants, pollen, fungi, fish, and "a great diversity of fossilised insects and arachnids," as well as a feather from a sparrow-sized bird's feather. Analysis of the preserved leaves reveals that the average temperature was approximately 63 degrees Fahrenheit (17 degrees Celsius).

McCurry told Live Science that he was most intrigued by the fossilised remains of spiders. McCurry reported that only four fossil spiders have been found in Australia before and that the discovery of 13 in McGrath Flats has changed that.

The soft tissues of the fish's eyes, skin, and feathers held another fascinating detail: melanosomes, pigment-storing cell structures. It's possible to compare the melanosomes' structure, size, and stacking patterns in fossils to those in present animals, even though they don't retain their colour. The study's co-author, University of Canberra associate professor of science Michael Frese, said in a statement that palaeontologists might often replicate ancient creatures' colours and patterns.

McGraths Flat has yielded many fossils, but "this is really only a small portion" of the fossil deposit, says McCurry. "It will take us years to characterise and name all of the species we find, but we now know how old the deposit is and how well-preserved the fossils are. As time goes on, I believe McGraths Flat will play a vital role in helping us better understand how Australia has evolved."

They were published Friday (Jan. 7) in Science Advances, the American Chemical Society journal.

Reference : https://www.livescience.com/secret-fossils-australia-spiders

Image source : https://www.livescience.com/secret-fossils-australia-spiders

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